Desktop Windows Composition and Windows 8.1 Pro x64

Hi, I'm Jenn, also new to these forums.
I stumbled upon a problem when switching from Windows 7 x64 to Windows 8.1 Pro x64.
I have the EXACT same setup, same laptop, same hardware, same programs, same configuration, everything.
Windows 7 never did anything like the problem I now have in Win 8.1. Here's the problem;

Whenever I run more than 1 3D application, after 1-5 minutes the screen blinks, and hangs the graphics of one, some or all the programs (randomly). It doesn't hang the actual program (or game), it just stops rendering the graphics -- I can still hear the software's sound and if I click around, I can hear myself interacting with it.
I have ALL the latest drivers for the computer, motherboard, ALL devices including graphics cards etc. Also ALL Windows Updates installed, nothing more to install.

All of the programs I use is specifically set to use only the nVidia adapter, forcibly through the nVidia Control Panel, so it's not a switching graphics problem because it's a laptop. Also, never was a problem in Windows 7 either.

So as you can see, DWM is logging in and out some account that can be all the way up to DWM-7 from what I've seen so far. It just logs in, sets some parameters and the directly logs out.
This is a ONE-user system, Only my user account is on it, and remote login has been disabled.
In Windows 7, at least DWM could be disabled - not that I ever had to, because it worked with all my stuff, but seeing as DWM is screwing up totally in Win8, I thought I'd just disable the server, but it's nowhere to be found.
Also, it seems Microsoft changed how it works, the system has been redesigned to generate an OK even if it's still on, like this example below:

DwmEnableComposition( DWM_EC_DISABLECOMPOSITION ) does not work on Windows 8, even though it returns S_OK. Confirmation is by calling DwmIsCompositionEnabled(), which shows the former function had no effect.